| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
| * |
| * $Date: 19. March 2015 |
| * $Revision: V.1.4.5 |
| * |
| * Project: CMSIS DSP Library |
| * Title: arm_fir_sparse_f32.c |
| * |
| * Description: Floating-point sparse FIR filter processing function. |
| * |
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * - Neither the name of ARM LIMITED nor the names of its contributors |
| * may be used to endorse or promote products derived from this |
| * software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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| * ------------------------------------------------------------------- */ |
| #include "arm_math.h" |
| |
| /** |
| * @ingroup groupFilters |
| */ |
| |
| /** |
| * @defgroup FIR_Sparse Finite Impulse Response (FIR) Sparse Filters |
| * |
| * This group of functions implements sparse FIR filters. |
| * Sparse FIR filters are equivalent to standard FIR filters except that most of the coefficients are equal to zero. |
| * Sparse filters are used for simulating reflections in communications and audio applications. |
| * |
| * There are separate functions for Q7, Q15, Q31, and floating-point data types. |
| * The functions operate on blocks of input and output data and each call to the function processes |
| * <code>blockSize</code> samples through the filter. <code>pSrc</code> and |
| * <code>pDst</code> points to input and output arrays respectively containing <code>blockSize</code> values. |
| * |
| * \par Algorithm: |
| * The sparse filter instant structure contains an array of tap indices <code>pTapDelay</code> which specifies the locations of the non-zero coefficients. |
| * This is in addition to the coefficient array <code>b</code>. |
| * The implementation essentially skips the multiplications by zero and leads to an efficient realization. |
| * <pre> |
| * y[n] = b[0] * x[n-pTapDelay[0]] + b[1] * x[n-pTapDelay[1]] + b[2] * x[n-pTapDelay[2]] + ...+ b[numTaps-1] * x[n-pTapDelay[numTaps-1]] |
| * </pre> |
| * \par |
| * \image html FIRSparse.gif "Sparse FIR filter. b[n] represents the filter coefficients" |
| * \par |
| * <code>pCoeffs</code> points to a coefficient array of size <code>numTaps</code>; |
| * <code>pTapDelay</code> points to an array of nonzero indices and is also of size <code>numTaps</code>; |
| * <code>pState</code> points to a state array of size <code>maxDelay + blockSize</code>, where |
| * <code>maxDelay</code> is the largest offset value that is ever used in the <code>pTapDelay</code> array. |
| * Some of the processing functions also require temporary working buffers. |
| * |
| * \par Instance Structure |
| * The coefficients and state variables for a filter are stored together in an instance data structure. |
| * A separate instance structure must be defined for each filter. |
| * Coefficient and offset arrays may be shared among several instances while state variable arrays cannot be shared. |
| * There are separate instance structure declarations for each of the 4 supported data types. |
| * |
| * \par Initialization Functions |
| * There is also an associated initialization function for each data type. |
| * The initialization function performs the following operations: |
| * - Sets the values of the internal structure fields. |
| * - Zeros out the values in the state buffer. |
| * To do this manually without calling the init function, assign the follow subfields of the instance structure: |
| * numTaps, pCoeffs, pTapDelay, maxDelay, stateIndex, pState. Also set all of the values in pState to zero. |
| * |
| * \par |
| * Use of the initialization function is optional. |
| * However, if the initialization function is used, then the instance structure cannot be placed into a const data section. |
| * To place an instance structure into a const data section, the instance structure must be manually initialized. |
| * Set the values in the state buffer to zeros before static initialization. |
| * The code below statically initializes each of the 4 different data type filter instance structures |
| * <pre> |
| *arm_fir_sparse_instance_f32 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; |
| *arm_fir_sparse_instance_q31 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; |
| *arm_fir_sparse_instance_q15 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; |
| *arm_fir_sparse_instance_q7 S = {numTaps, 0, pState, pCoeffs, maxDelay, pTapDelay}; |
| * </pre> |
| * \par |
| * |
| * \par Fixed-Point Behavior |
| * Care must be taken when using the fixed-point versions of the sparse FIR filter functions. |
| * In particular, the overflow and saturation behavior of the accumulator used in each function must be considered. |
| * Refer to the function specific documentation below for usage guidelines. |
| */ |
| |
| /** |
| * @addtogroup FIR_Sparse |
| * @{ |
| */ |
| |
| /** |
| * @brief Processing function for the floating-point sparse FIR filter. |
| * @param[in] *S points to an instance of the floating-point sparse FIR structure. |
| * @param[in] *pSrc points to the block of input data. |
| * @param[out] *pDst points to the block of output data |
| * @param[in] *pScratchIn points to a temporary buffer of size blockSize. |
| * @param[in] blockSize number of input samples to process per call. |
| * @return none. |
| */ |
| |
| void arm_fir_sparse_f32( |
| arm_fir_sparse_instance_f32 * S, |
| float32_t * pSrc, |
| float32_t * pDst, |
| float32_t * pScratchIn, |
| uint32_t blockSize) |
| { |
| |
| float32_t *pState = S->pState; /* State pointer */ |
| float32_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */ |
| float32_t *px; /* Scratch buffer pointer */ |
| float32_t *py = pState; /* Temporary pointers for state buffer */ |
| float32_t *pb = pScratchIn; /* Temporary pointers for scratch buffer */ |
| float32_t *pOut; /* Destination pointer */ |
| int32_t *pTapDelay = S->pTapDelay; /* Pointer to the array containing offset of the non-zero tap values. */ |
| uint32_t delaySize = S->maxDelay + blockSize; /* state length */ |
| uint16_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */ |
| int32_t readIndex; /* Read index of the state buffer */ |
| uint32_t tapCnt, blkCnt; /* loop counters */ |
| float32_t coeff = *pCoeffs++; /* Read the first coefficient value */ |
| |
| |
| |
| /* BlockSize of Input samples are copied into the state buffer */ |
| /* StateIndex points to the starting position to write in the state buffer */ |
| arm_circularWrite_f32((int32_t *) py, delaySize, &S->stateIndex, 1, |
| (int32_t *) pSrc, 1, blockSize); |
| |
| |
| /* Read Index, from where the state buffer should be read, is calculated. */ |
| readIndex = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; |
| |
| /* Wraparound of readIndex */ |
| if(readIndex < 0) |
| { |
| readIndex += (int32_t) delaySize; |
| } |
| |
| /* Working pointer for state buffer is updated */ |
| py = pState; |
| |
| /* blockSize samples are read from the state buffer */ |
| arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, |
| (int32_t *) pb, (int32_t *) pb, blockSize, 1, |
| blockSize); |
| |
| /* Working pointer for the scratch buffer */ |
| px = pb; |
| |
| /* Working pointer for destination buffer */ |
| pOut = pDst; |
| |
| |
| #ifndef ARM_MATH_CM0_FAMILY |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| /* Loop over the blockSize. Unroll by a factor of 4. |
| * Compute 4 Multiplications at a time. */ |
| blkCnt = blockSize >> 2u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiplications and store in destination buffer */ |
| *pOut++ = *px++ * coeff; |
| *pOut++ = *px++ * coeff; |
| *pOut++ = *px++ * coeff; |
| *pOut++ = *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* If the blockSize is not a multiple of 4, |
| * compute the remaining samples */ |
| blkCnt = blockSize % 0x4u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiplications and store in destination buffer */ |
| *pOut++ = *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* Load the coefficient value and |
| * increment the coefficient buffer for the next set of state values */ |
| coeff = *pCoeffs++; |
| |
| /* Read Index, from where the state buffer should be read, is calculated. */ |
| readIndex = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; |
| |
| /* Wraparound of readIndex */ |
| if(readIndex < 0) |
| { |
| readIndex += (int32_t) delaySize; |
| } |
| |
| /* Loop over the number of taps. */ |
| tapCnt = (uint32_t) numTaps - 2u; |
| |
| while(tapCnt > 0u) |
| { |
| |
| /* Working pointer for state buffer is updated */ |
| py = pState; |
| |
| /* blockSize samples are read from the state buffer */ |
| arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, |
| (int32_t *) pb, (int32_t *) pb, blockSize, 1, |
| blockSize); |
| |
| /* Working pointer for the scratch buffer */ |
| px = pb; |
| |
| /* Working pointer for destination buffer */ |
| pOut = pDst; |
| |
| /* Loop over the blockSize. Unroll by a factor of 4. |
| * Compute 4 MACS at a time. */ |
| blkCnt = blockSize >> 2u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* If the blockSize is not a multiple of 4, |
| * compute the remaining samples */ |
| blkCnt = blockSize % 0x4u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* Load the coefficient value and |
| * increment the coefficient buffer for the next set of state values */ |
| coeff = *pCoeffs++; |
| |
| /* Read Index, from where the state buffer should be read, is calculated. */ |
| readIndex = ((int32_t) S->stateIndex - |
| (int32_t) blockSize) - *pTapDelay++; |
| |
| /* Wraparound of readIndex */ |
| if(readIndex < 0) |
| { |
| readIndex += (int32_t) delaySize; |
| } |
| |
| /* Decrement the tap loop counter */ |
| tapCnt--; |
| } |
| |
| /* Compute last tap without the final read of pTapDelay */ |
| |
| /* Working pointer for state buffer is updated */ |
| py = pState; |
| |
| /* blockSize samples are read from the state buffer */ |
| arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, |
| (int32_t *) pb, (int32_t *) pb, blockSize, 1, |
| blockSize); |
| |
| /* Working pointer for the scratch buffer */ |
| px = pb; |
| |
| /* Working pointer for destination buffer */ |
| pOut = pDst; |
| |
| /* Loop over the blockSize. Unroll by a factor of 4. |
| * Compute 4 MACS at a time. */ |
| blkCnt = blockSize >> 2u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* If the blockSize is not a multiple of 4, |
| * compute the remaining samples */ |
| blkCnt = blockSize % 0x4u; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| blkCnt = blockSize; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiplications and store in destination buffer */ |
| *pOut++ = *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* Load the coefficient value and |
| * increment the coefficient buffer for the next set of state values */ |
| coeff = *pCoeffs++; |
| |
| /* Read Index, from where the state buffer should be read, is calculated. */ |
| readIndex = ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; |
| |
| /* Wraparound of readIndex */ |
| if(readIndex < 0) |
| { |
| readIndex += (int32_t) delaySize; |
| } |
| |
| /* Loop over the number of taps. */ |
| tapCnt = (uint32_t) numTaps - 2u; |
| |
| while(tapCnt > 0u) |
| { |
| |
| /* Working pointer for state buffer is updated */ |
| py = pState; |
| |
| /* blockSize samples are read from the state buffer */ |
| arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, |
| (int32_t *) pb, (int32_t *) pb, blockSize, 1, |
| blockSize); |
| |
| /* Working pointer for the scratch buffer */ |
| px = pb; |
| |
| /* Working pointer for destination buffer */ |
| pOut = pDst; |
| |
| blkCnt = blockSize; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* Load the coefficient value and |
| * increment the coefficient buffer for the next set of state values */ |
| coeff = *pCoeffs++; |
| |
| /* Read Index, from where the state buffer should be read, is calculated. */ |
| readIndex = |
| ((int32_t) S->stateIndex - (int32_t) blockSize) - *pTapDelay++; |
| |
| /* Wraparound of readIndex */ |
| if(readIndex < 0) |
| { |
| readIndex += (int32_t) delaySize; |
| } |
| |
| /* Decrement the tap loop counter */ |
| tapCnt--; |
| } |
| |
| /* Compute last tap without the final read of pTapDelay */ |
| |
| /* Working pointer for state buffer is updated */ |
| py = pState; |
| |
| /* blockSize samples are read from the state buffer */ |
| arm_circularRead_f32((int32_t *) py, delaySize, &readIndex, 1, |
| (int32_t *) pb, (int32_t *) pb, blockSize, 1, |
| blockSize); |
| |
| /* Working pointer for the scratch buffer */ |
| px = pb; |
| |
| /* Working pointer for destination buffer */ |
| pOut = pDst; |
| |
| blkCnt = blockSize; |
| |
| while(blkCnt > 0u) |
| { |
| /* Perform Multiply-Accumulate */ |
| *pOut++ += *px++ * coeff; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| #endif /* #ifndef ARM_MATH_CM0_FAMILY */ |
| |
| } |
| |
| /** |
| * @} end of FIR_Sparse group |
| */ |
